The present application claims priority to Japanese Application(s) No(s). P2001-050907 Feb. 26, 2001, which application(s) is/are incorporated herein by reference to the extent permitted by law.
1. Field of the Invention
This invention relates to portable equipment incorporating a magnetic disk device, such as a portable telephone set, digital camcorder, digital still camera, and portable audio equipment.
2. Description of the Related Art
In recent years, there has been remarkable progress in so-called battery-driven portable information equipment, such as portable telephones, digital camcorders, digital still cameras, and portable audio equipment. Semiconductor memory is used extensively in such recording devices incorporated in portable equipment, and storage capacities are being increased
At present, 128 MB (megabyte) semiconductor memory devices are commercially marketed, and it has become possible to easily carry on one""s person the image and audio data and other data downloaded from various Internet web sites However, still greater storage capacities are necessary to record high-resolution images or video files.
In order to realize such large capacities, recently portable equipment capable of incorporating small-size magnetic disk devices, measuring from 1 to 2.5 inches, has been released commercially. Such small-size magnetic disk devices have capacities of approximately 1 GB (gigabyte), or approximately ten times that of a semiconductor memory device, so that 100 or so high-resolution images of size up to 10 MB, or video files equivalent to 30 minutes of DVD (Digital Video Disc) data, can be recorded.
However, there is the problem that, in general, so-called hard disk-type magnetic disk devices are vulnerable to shocks. In order to achieve high recording densities, a magnetic head levitates or xe2x80x9cfliesxe2x80x9d above the surface of the rotating magnetic disk with an extremely small interval of 20 nm to 50 nm between the head and the magnetic disk surface, and there is a tendency for this flying height to be further reduced.
When a shock from outside is applied to a device in which a magnetic head is flying at such a low flying height, the magnetic head and magnetic disk collide, a large scratch is formed on the magnetic disk surface, and recorded data is destroyed. If the shock is great, the magnetic head itself may be damaged as well.
Consequently magnetic disk devices often adopt glass magnetic disks or similar with high hardness, and, when the device is mounted in portable information equipment, other measures are taken as well, such as providing cushioning material in the vicinity of the magnetic disk device.
For example, when damage due to a shock occurs in a portion of a magnetic disk, so that data in this portion is destroyed, if the data is information used to manage the data written to the magnetic disk, it is even possible that all the data on the magnetic disk may be lost.
The present invention relates to portable equipment incorporating a magnetic disk device, in which the magnetic disk device is provided with a magnetic head retraction mechanism and a held-in-hand detection mechanism which detects when the equipment is held in one""s hand, and configured such that, when this held-in-hand detection mechanism detects that the equipment is not held in one""s hand, the retraction mechanism retracts the magnetic head from the recorded data portion of the magnetic disk to the outside, to protect the magnetic disk device, and data recorded on the magnetic disk, from shocks.
In the present invention, the above-described held-in-hand detection mechanism is configured as a mechanism which detects changes in electrostatic capacitance.
In the present invention, the above-described held-in-hand detection mechanism is configured as a mechanism which detects optical changes.
In the present invention, the above-described held-in-hand detection mechanism is configured as a mechanism which detects changes in infrared rays.
In the present invention, the above-described held-in-hand detection mechanism is configured to perform detection by a mechanical mechanism.
That is, in order to resolve the problems described above, in the present invention, damage to data caused by shocks is held to a minimum by causing a held-in-hand detection mechanism, which detects whether the portable equipment is being held by a human, and the magnetic head retraction mechanism, to operate synchronously.
There are current magnetic disk devices in which a mechanism for head retraction when not in operation is provided FIG. 10 is a summary plane view of one such example. In FIG. 10, 1 is a magnetic disk device, 2 is a spindle motor, 3 is a magnetic disk, 4 is a rotary actuator, 5 is a magnetic head, and 7 is a ramp which serves as the retraction position. 6 is a load plate which is a support mechanism provided to avoid contact between the magnetic head 5 and ramp 7 in the event of retraction of the magnetic head to the ramp.
As shown in FIG. 10, during operation the magnetic head 5 fixed at the tip of the rotary actuator 4 moves in, for example, the radial direction and records data to and reproduces data from the rotating magnetic disk 3, while maintaining a very small interval between the magnetic head 5 and the surface of the magnetic disk 3.
When not in operation, as shown in FIG. 11 by the summary plane view of the example, the tip of the rotary actuator 4 is configured so as to move onto the ramp provided adjacent to the magnetic disk 3, in this case the load plate 6 is placed on top of the ramp 7 such that contact between the magnetic head 5 and the surface of the ramp 7 is avoided, in FIG. 11, portions corresponding to those in FIG. 10 are assigned the same symbols, and redundant explanations are omitted.
As shown by the schematic diagram of the manner of motion of the load plate 6 in FIG. 12, the ramp 7 is provided with a taper portion 7a which continues smoothly from the surface of the magnetic disk 3, and a placement portion 7b; as a result of movement of the rotary actuator 4 from above the magnetic disk 3, the load plate 6 rises along the taper portion 7a of the ramp 7 and is placed on the placement portion 7b, as indicated by the arrow a. By making the placement portion 7b lower than the upper end of the taper portion 7a, as shown in the figure, stable placement on the placement portion 7b is possible.
The main object of this retraction mechanism is to prevent the magnetic head 5 from adhering to the magnetic disk 3, as a result of contact between the magnetic head 5 and the surface of the magnetic disk 3 upon cessation of rotation of the magnetic disk 3 when not in operation.
However, this retraction mechanism also contributes to improvement of shock resistance. This is because when a large shock is applied from outside while the magnetic head is retracted, even if the magnetic head vibrates; it is not superposed on the magnetic disk, and so contact with the magnetic disk can be avoided.
Among the magnetic disk devices that are currently marketed commercially there are devices which have a shock resistance during operation of from 100 to 200 G (peak value of a one-half sine wave shock of length 2 ms) (where G is gravitational acceleration); but there are devices which can withstand shocks of 1500 G when not in operation. This difference in shock resistance is due to the above-described magnetic head retraction mechanism.
Hence in portable information equipment incorporating such a magnetic disk device, if a shock from outside can be anticipated, and the magnetic head is retracted by the retraction mechanism before the shock is received, the possibility of damage can be reduced.
Most large shocks born by portable equipment are due to slipping off the hand while being held by a person as a result of carelessness, or to otherwise being separated from one""s hand and falling. If the portable equipment is being held by a person by some means, evasive action to avoid a shock, or protective action such as covering the equipment with one""s hand, can be taken in that instant.
By means of this invention, a held-in-hand detection mechanism can be used to quickly detect a state in which there is a high probability of a collision, that is, a state of separation from the hand of a person, the magnetic head of the magnetic disk device can be retracted prior to the collision, and the equipment can be put into a shock-resistant state, so that considerable damage can be prevented.
Normally, the time for an object to fall from the height of a desk, for example 70 cm, and collide with the floor is 0.38 seconds. On the other hand, the time required for retraction of the magnetic head in the above-described magnetic disk device is, at most, several tens of milliseconds. Hence in the case of a fall from a certain height, retraction within the time until the collision is entirely possible, that is, avoidance of the shock is possible.